1 files changed, 40 insertions, 0 deletions
diff --git a/browser/components/sessionstore/test/browser_swapDocShells.js b/browser/components/sessionstore/test/browser_swapDocShells.js
new file mode 100644
index 0000000000..047a36c510
--- /dev/null
+++ b/browser/components/sessionstore/test/browser_swapDocShells.js
@@ -0,0 +1,40 @@
+"use strict";
+
+add_task(async function () {
+  let tab = (gBrowser.selectedTab = BrowserTestUtils.addTab(
+    gBrowser,
+    "about:mozilla"
+  ));
+  await promiseBrowserLoaded(gBrowser.selectedBrowser);
+
+  let win = gBrowser.replaceTabWithWindow(tab);
+  await promiseDelayedStartupFinished(win);
+  await promiseBrowserHasURL(win.gBrowser.browsers[0], "about:mozilla");
+
+  win.duplicateTabIn(win.gBrowser.selectedTab, "tab");
+  await promiseTabRestored(win.gBrowser.tabs[1]);
+
+  let browser = win.gBrowser.browsers[1];
+  is(browser.currentURI.spec, "about:mozilla", "tab was duplicated");
+
+  await BrowserTestUtils.closeWindow(win);
+});
+
+function promiseDelayedStartupFinished(win) {
+  return new Promise(resolve => {
+    whenDelayedStartupFinished(win, resolve);
+  });
+}
+
+function promiseBrowserHasURL(browser, url) {
+  let promise = Promise.resolve();
+
+  if (
+    browser.contentDocument.readyState === "complete" &&
+    browser.currentURI.spec === url
+  ) {
+    return promise;
+  }
+
+  return promise.then(() => promiseBrowserHasURL(browser, url));
+}